EP1007744A1 - Procede de desiliciage de fonte brute avant un affinage en acier - Google Patents

Procede de desiliciage de fonte brute avant un affinage en acier

Info

Publication number
EP1007744A1
EP1007744A1 EP99924566A EP99924566A EP1007744A1 EP 1007744 A1 EP1007744 A1 EP 1007744A1 EP 99924566 A EP99924566 A EP 99924566A EP 99924566 A EP99924566 A EP 99924566A EP 1007744 A1 EP1007744 A1 EP 1007744A1
Authority
EP
European Patent Office
Prior art keywords
slag
pig iron
steel
iron
content
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99924566A
Other languages
German (de)
English (en)
Inventor
Alfred Edlinger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Holcim Ltd
Original Assignee
Holderbank Financiere Glarus AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Holderbank Financiere Glarus AG filed Critical Holderbank Financiere Glarus AG
Publication of EP1007744A1 publication Critical patent/EP1007744A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/04—Removing impurities other than carbon, phosphorus or sulfur
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B3/00—General features in the manufacture of pig-iron
    • C21B3/04—Recovery of by-products, e.g. slag
    • C21B3/06—Treatment of liquid slag
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2400/00—Treatment of slags originating from iron or steel processes
    • C21B2400/02—Physical or chemical treatment of slags
    • C21B2400/022—Methods of cooling or quenching molten slag
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

Definitions

  • the invention relates to a method for the desilication of pig iron before a subsequent refining to steel.
  • Blast furnace pig iron generally contains about 0.4 to 2.8% silicon and over 4% by weight carbon.
  • silicon is oxidized to SiO 2 and carbon to carbon monoxide, whereby in the course of the freshening process, iron burn-off due to the oxygen supply cannot be prevented.
  • the slag that forms during steel refining is usually obtained as a strongly basic slag, since a correspondingly high lime scale has to be added, which is partially neutralized by the SiO 2 formed.
  • the high basicity of such steel slags and the high proportion of iron and chromium oxides and, if appropriate, heavy metal oxides do not readily allow the direct use of steel slags for reasons of possible toxicity.
  • blast furnace slag While blast furnace slag has favorable hydraulic properties and a significantly lower iron oxide content and can therefore be more easily recycled as a building material, the disposal of steelworks slags is becoming increasingly difficult, since such steelworks slags in the resulting composition, i.e. without subsequent metallurgical processing not easily for construction purposes or the like. are usable.
  • Metallurgical processing of the steelworks slag is usually associated with high energy consumption and high investment costs.
  • the invention now aims to make better use of the heat balance of converting pig iron with steel slag and, at the same time, to provide a starting product for the subsequent refining, in which the amount of slag during the refining and in particular the lime scale is reduced and at the same time the iron discharge is improved can.
  • the process according to the invention essentially consists in that liquid steel slag in an amount corresponding to the Si content of the pig iron and the Fe and / or Cr oxide content of the slag after blast furnace tapping on the tapped pig iron and if necessary, the blast furnace slag bath is abandoned, the amount is such that the Si content of the pig iron to less than 0.5% by weight with a simultaneous increase in the SiO 2 content of the slag with reduction of Fe and / or Cr oxides Slag is brought to liquid metals and that the slag iron bath temperature is kept below 1500 ° C.
  • the coordination of the amount of steel slag added to the desired final value of the silicon content thus allows a particularly economical procedure in which the subsequent steel production process is in no way impaired, but on the contrary, on the contrary, due to the lower amounts of SiO 2 in the steel refining process, is improved.
  • the simultaneous mixing with possibly existing blast furnace slag in the pig iron trough or the pig iron mixer or a ladle leads to a reduction in the reaction speed due to the resulting dilution and thus to a reduction in the fresh enthalpy, but at the same time the quality of the slag, which in particular was already improved in that iron and chromium oxides could be reduced to liquid metals, improved and their disposal or reuse is facilitated.
  • the slag iron bath temperature is kept below 1500 ° C. Above this temperature, carbon reacts preferentially with the iron oxide of the steel slag, because above this temperature carbon becomes less noble than silicon. Only the limitation of the temperatures to 1500 ° C enables an economically sensible desilication and prevents the otherwise possible explosive eruptions of the slag iron bath through spontaneous, uncontrollable carbon monoxide formation.
  • the temperature control which is the result of adding scrap, adding cold slag, dissipating heat, introducing gas or the like, is therefore of crucial importance for carrying out the method according to the invention. can be controlled accordingly, as will be explained in more detail below.
  • the process according to the invention is advantageously carried out in such a way that the Si content of the pig iron is brought to below 0.2% by weight.
  • the process according to the invention can be carried out without great expenditure on plant technology, the process preferably being carried out in such a way that the steel slag is fed into a pig iron mixer or a ladle, in particular a torpedo ladle.
  • a pig iron mixer or a ladle in particular a torpedo ladle.
  • steel slag is added in an amount which is less than 1/2, preferably less than 1 / 4 of the amount of blast furnace slag. Limiting the amount of steel slag also makes it possible to take the refractory problem into account, since the desired basic slag basicity can be set in this way. Instead of the blast furnace slag quantity, the remaining reduced slag quantity can naturally also be included in this calculation of the quantities.
  • the positive heat balance allows additives, such as Al2O3, to be melted, so that an optimal composition can be guaranteed for subsequent use in the manufacture of hydraulic binders. It is advantageous to proceed in such a way that additives such as e.g. AI2O3 in quantities of 50 to 180 kg / t slag are added, the heat balance being sufficient to melt such quantities of AI2O3.
  • additives such as e.g. AI2O3 in quantities of 50 to 180 kg / t slag are added, the heat balance being sufficient to melt such quantities of AI2O3.
  • the procedure is advantageously such that the steel slag is fed in via an adjustable or controllable feed device which is dependent on the steel slag and the blast furnace slag composition and the pig iron bath composition is regulated or controlled.
  • the reaction rate and the complete conversion can be further improved by blowing inert gases, in particular nitrogen, into the pig iron / slag mixture tapped from the blast furnace.
  • the temperature control to ⁇ 1500 ° C can also be carried out by adding cold additives, cold slag and / or scrap.
  • Pig iron mixers are used in integrated steelworks as a raw iron buffer between the blast furnace and the steel converter, the capacity of such pig iron mixers usually corresponding to at least one daily steel mill production.
  • the storage of such a daily steel mill production in the pig iron mixer also serves to even out the pig iron quality.
  • mobile torpedo pans are also used, in which the mixing is promoted by the independent swiveling of the contents during transport from the blast furnace to the steelworks.
  • the liquid slag to be reduced is advantageously introduced and the blast furnace pig iron is poured on, which ensures high turbulence and intensive conversion.
  • the phosphorus that is possibly introduced into the pig iron bath by steel slag is slagged by the subsequent oxidizing refining process.
  • Another possibility to interrupt the phosphorus cycle is to dephosphorize the pig iron bath under reducing conditions. This is done by introducing calcium carbide or fine lime.
  • the high-phosphorus intermediate slag can be converted into high-quality chromium-free fertilizer by oxidative aftertreatment.
  • additives such as steel dusts and other silicate and aluminate-containing metallurgical residues
  • the acidic additives such as A1203 and possibly further SiO 2
  • Additives containing SiO 2 have to be compared to conventional slag processes much smaller amounts are added, since SiO 2 is formed immediately when the steel slag is converted with the pig iron bath. It is also advantageous that the pig iron is at least partially desulfurized by the slag CaO content.
  • the method according to the invention can preferably be carried out with a specially adapted device.
  • a device for carrying out the method is essentially characterized by a trough for pig iron, on the bottom of which gutters or openings for the introduction of inert gases are arranged and into which a slag feeder and a blast furnace pig iron feeder opens and a pan connected downstream of the trough for the separation of slag and iron bath.
  • the turbulence can be increased by the inert gases and in particular by pressure nitrogen, so that better mixing is ensured at the same time as better heat dissipation.
  • Channel fumigation thus ensures that local overheating cannot occur and that the temperature can be reliably kept below 1500 ° C.
  • the device is advantageously developed in such a way that the trough opens into an immersion tube which projects into the iron bath of the pan.
  • an immersion tube which projects into the iron bath of the separating pan, the reduction distance of the ascending droplets of slag is increased and a complete implementation is ensured.
  • intensive mixing can also be achieved in that the channel is designed as a cascade, the slag overflow of a subsequent cascade stage being arranged below the level of the inflow of the iron bath from the previous cascade stage.
  • FIG. 1 shows a plan view of a device according to the invention for carrying out the method
  • FIG. 2 shows a schematic side view, partly in section through parts of a device according to FIG. 1.
  • Fig. 1 schematically indicates a steel slag pan
  • 2 denotes a pig iron pan.
  • the amounts of slag drawn off from the steel slag ladle, as well as the amount of pig iron, are fed to a channel 4 via appropriately controlled throttling elements 3 and subsequently reach a separating pan 5 in which the iron bath is separated from the slag.
  • FIG. 2 again designates the steel slag pan, to which a slag tundish 6 is connected, the slag feeder of which is designated 7.
  • the steel slag reaches the trough 4, it being apparent from the illustration according to FIG. 2 that inert gas is introduced under pressure and in particular nitrogen through openings 8 in the bottom of the trough.
  • the trough 4, as schematically indicated in FIG. 1, is separately fed in pig iron, optionally mixed with blast furnace slag.
  • the material largely desilated in the trough subsequently passes into a funnel 9 of an immersion tube 10, which opens below the iron bath 11 of the separating pan 5.
  • the ascending droplets of slag are further reduced and a chromate-free slag 12 floats on the iron bath 11 in the separating pan 5, which can be applied separately.
  • the trough 4 can be adjusted in its inclination by means of a corresponding hydraulic device 13, the flow velocity and the turbulence being adjusted accordingly here together with the pressure nitrogen of the trough gassing can, in order to achieve optimal heat dissipation, so that the desired limitation of the temperature of the reaction is reliably maintained.
  • the temperature can also be kept below 1500 ° C. by a cooling wind box, not shown, above the channel.
  • a converter slag with the following composition was used:
  • the pig iron present in the pig iron mixer has 1% Si and 4.6% C. 150 kg of ready-made converter slag are placed on 1 t of pig iron. Assembled means that the CaO / SiO 2 basicity has been reduced from 3.14 in the pan and the AI2O3 content has been increased to 10%.
  • the pig iron present contained 10 kg Si / t pig iron (1% in pig iron), so that after the reaction there was 2 kg Si / t pig iron or 0.2% Si in the pig iron.
  • the slag reduction using silicon is exothermic, so that no additional energy had to be added for this process.
  • the slag reduction produced SiO 2 in the following quantities:
  • AI2O3 content served primarily to improve the early strength of hydraulic binders made from such slags.
  • the method according to the invention results in a small additional investment volume and practically no additional energy requirement. Furthermore, the addition of SiO 2 becomes significantly less, since the basicity is sufficiently reduced in the course of the process by the SiO 2 formed by the fresh silicon.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

Lors d'un procédé de désiliciage de fonte brute qui précède un affinage en acier, on dépose des scories d'acier liquide sur le bain de fonte brute coulée et éventuellement sur le bain de scories des hauts fourneaux, et ce dans une quantité correspondant à la teneur en silicium de la fonte brute et à la teneur en fer et/ou oxyde de chrome des scories après la coulée des hauts fourneaux. La quantité des scories d'acier est mesurée de telle façon que la teneur en silicium de la fonte brute est ramenée en-deçà de 0,5 % en poids pour une augmentation simultanée de la teneur en SiO2 des scories avec réduction des oxydes de fer et/ou de chrome des scories en métaux liquides. La température du bain de fer des scories est maintenue inférieure à 1500 °C.
EP99924566A 1998-06-10 1999-06-09 Procede de desiliciage de fonte brute avant un affinage en acier Withdrawn EP1007744A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AT0100698A AT406691B (de) 1998-06-10 1998-06-10 Verfahren zum entsilizieren von roheisen vor einem frischen zu stahl
AT100698 1998-06-10
PCT/AT1999/000149 WO1999064635A1 (fr) 1998-06-10 1999-06-09 Procede de desiliciage de fonte brute avant un affinage en acier

Publications (1)

Publication Number Publication Date
EP1007744A1 true EP1007744A1 (fr) 2000-06-14

Family

ID=3504771

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99924566A Withdrawn EP1007744A1 (fr) 1998-06-10 1999-06-09 Procede de desiliciage de fonte brute avant un affinage en acier

Country Status (9)

Country Link
US (1) US6261339B1 (fr)
EP (1) EP1007744A1 (fr)
AT (1) AT406691B (fr)
BR (1) BR9906496A (fr)
CA (1) CA2299277A1 (fr)
ES (1) ES2149752T1 (fr)
SK (1) SK1262000A3 (fr)
WO (1) WO1999064635A1 (fr)
ZA (1) ZA200000582B (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007028423A1 (fr) 2005-09-09 2007-03-15 Robert Bosch Gmbh Console de discussion pour système de conférence à modules interchangeables

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS538310A (en) 1976-07-13 1978-01-25 Nippon Steel Corp Reusing method of steel making slag
JPS58181815A (ja) 1982-04-19 1983-10-24 Nippon Kokan Kk <Nkk> 転炉による溶銑の予備脱硅方法
JPS59104414A (ja) 1982-12-07 1984-06-16 Nippon Steel Corp 溶銑の脱珪方法
JPS60218408A (ja) 1984-04-13 1985-11-01 Sumitomo Metal Ind Ltd 溶銑の予備処理方法
JPS6318011A (ja) 1986-07-10 1988-01-25 Kawasaki Steel Corp 溶銑の予備処理方法
JPH01156413A (ja) 1987-12-11 1989-06-20 Nisshin Steel Co Ltd 溶銑の予備処理法および装置
JPH032308A (ja) 1989-05-31 1991-01-08 Nkk Corp 溶銑予備処理方法
DE4242328C2 (de) * 1992-12-15 1995-06-08 Alfred Dipl Ing Dr Freissmuth Mittel zur Entschwefelung, Entphosphorung, Entsilicierung und Entstickung von Roheisen- und Gußeisenschmelzen
ATE151118T1 (de) 1993-09-07 1997-04-15 Holderbank Financ Glarus Verfahren zum herstellen von stahl und hydraulisch aktiven bindemitteln

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9964635A1 *

Also Published As

Publication number Publication date
ES2149752T1 (es) 2000-11-16
CA2299277A1 (fr) 1999-12-16
WO1999064635A1 (fr) 1999-12-16
BR9906496A (pt) 2000-09-26
ATA100698A (de) 1999-12-15
AT406691B (de) 2000-07-25
ZA200000582B (en) 2001-03-12
SK1262000A3 (en) 2000-09-12
US6261339B1 (en) 2001-07-17

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